Multi-component electronic devices and methods for making them

ABSTRACT

Electronic devices include at least two electronic components in electrical contact by a connector, the components being at least partially encased by a molded resin. Preferably, the connector is a compression connector and the molded resin maintains a compressive force on the connector to ensure that reliable contact is maintained.

This is a continuation of application Ser. No. 08/556,677 filed on Nov.13, 1995, now abandoned, which is a divisional application ofapplication Ser. No. 08/359,973 filed Dec. 20, 1994 now U.S. Pat. No.5,607,882.

TECHNICAL FIELD

This disclosure relates generally to electronic devices having at leasttwo components interconnected by electrical connectors. Morespecifically, this disclosure relates to multi-component electricaldevices wherein the components are at least partially encased in amolded resin.

BACKGROUND

Electronic devices generally include a plurality of components inelectrical contact. For example, a simple electronic device may includea circuit board as a first component and a display (e.g., an LCDdisplay) as a second component. Other more complex electronic devicesmay include several circuit boards, displays and/or I/O devices.

Electrical contact between the components can be accomplished in avariety of ways. For example, rigid metal contacts can be provided andmade secure by soldering. As another example, compression connectors maybe used to provide electrical connections between the components. Toensure reliable contact between the components, compression connectorsmust be maintained in a compressed state. Set screws or other mechanicalfasteners are commonly used to secure the components together andmaintain the compression connectors in a compressed state.

In assembling an electronic device which includes compressionconnectors, the components are normally aligned with the compressionconnector positioned between the components. Set screws or othersecurement devices are then applied to hold the components together. Theassembled components can then be placed within and secured to a housing.Normally, a two-part housing is employed requiring an additional step tosecure the two halves of the housing together.

The completed electronic device will perform satisfactorily only if theconnections between the components provide reliable contact. Thus, theassembly of the device must be performed with precision. In addition,the reliability of the connections can be compromised by jostling duringshipping or handling, or when the device is dropped onto a hard surface.

As the foregoing discussion demonstrates, assembly of multi-componentelectronic devices may be very labor-intensive and the reliability ofthe connections between the components of the device is subject to greatvariability. It would be desirable to provide a more efficient method ofassembling the components of a multi-component electronic device,particularly those employing compression connectors, in a manner whichprovides reliable connections, and mechanically and environmentallyrobust electronic devices.

SUMMARY

Electronic devices in accordance with this disclosure include at leasttwo components in electrical contact by connector means, the componentsbeing at least partially encased by a molded, monolithic resincomponent. In particularly useful embodiments, the connector means is acompression connector and the resin component maintains the compressiveforce necessary to ensure the connector provides reliable electricalcontact.

In another aspect, a method for producing electronic devices has beendiscovered wherein at least two components of an electronic device witha connector therebetween are placed between two halves of a mold. Whenthe mold halves close, the components are captured within the moldcavity and are placed into close proximity, completing an electricalinterconnection. A resin material is then introduced into the moldcavity and hardens to fully or partially encase the components. When thefinished device is removed from the mold, the components are heldtogether by the hardened resin.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are described herein with reference to the drawingswherein:

FIG. 1 is a perspective view of an electronic device made in accordancewith this disclosure;

FIG. 2 is an exploded perspective view of components useful in making adevice in accordance with this disclosure prior to molding;

FIG. 3 is a perspective view of a stacked assembly of the components ofFIG. 2 prior to molding;

FIG. 4. is a perspective view of a mold half useful in making electronicdevices in accordance with this disclosure;

FIG. 5 is a perspective view of another molding apparatus and componentsuseful in making electronic devices in accordance with this disclosure;and

FIG. 6 is a perspective view of the apparatus of FIG. 5 after molding.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, an electronic device is generally denoted by thenumeral 10 and includes at least two components, such as display 12 anda second component not visible in FIG. 1 but discussed hereinafter, anda molded, monolithic resin component 15 which at least partially encasesthe two components. Unless the context indicates otherwise, the term“resin” as used herein is intended to embrace any natural or syntheticpolymer capable of being molded. The term “electronic device” as usedherein is intended to embrace both finished consumer products as well asmodular devices or parts to be incorporated into products. The term“electronic component” as used herein is intended to embrace any type ofstructure which is incorporated into an electronic device and iselectronically connected to another structure in the device. Suchcomponents include, but are not limited to printed wiring boards,integrated circuits, discrete components, connectors, flex circuits,displays, I/O interfaces, keypads and other input devices, and housings.

To make electronic device 10, display 12 and a circuit board 16 arealigned as shown in FIG. 2 with a compression connector 19 positionedtherebetween. While an elastomeric compression connector is shown inFIG. 2, any of the other types of compression connectors known to thoseskilled in the art may be employed. In addition, known types of rigidconnectors, though less preferred, can be employed.

As best seen in FIG. 3, stacked assembly 20 is prepared by positioningthe display 12 and circuit board 16 onto either side of connector 19.Where a rigid connector is employed, the electrical contact can besecured once the assembly is prepare. Self-securing connectors (e.g.,pin and socket, press fit, etc.) are particularly useful rigidconnectors for use in the present methods and devices since suchconnectors can be assembled by the closing of a mold around theassembly, effectively eliminating the need to employ a separate securingstep.

Stacked assembly 20 is then placed into mold 25 shown in FIG. 4 so thata resin can be introduced into the mold to at least partially encase thestacked assembly. Mold 25 includes a cavity 27 which is dimensioned andconfigured to receive stacked assembly 20. Precision alignment is notrequired during preparation of stacked assembly 20, since the side wallsof mold cavity 27 will serve as alignment means. It is also contemplatedthat the mold can be provided with pins (not shown) or other alignmentmeans to ensure proper alignment of the components within mold cavity27. Where alignment means are provided, it is further contemplated thatthe components may be individually positioned in the mold cavity, ratherthan as a stacked assembly.

As is conventional in molding devices, mold 25 includes one or morerunners 29 for delivering molten or uncured resin to cavity 27 and ismounted to a platen 31. A second mold half (not shown) can be moved intocontact with mold 25 to provide an enclosed cavity into which resin canbe introduced. The closing of the mold halves provides the compressiveforce necessary to ensure reliable electrical connection between thecomponents. Optionally, one or both of the mold halves can be providedwith pins (not shown) which extend into cavity 27 such that upon closingof the mold halves circuit board 16 and display 12 are pressed togetherby the pins, thereby compressing connector 19.

The configuration of the mold halves is not critical provided that thecavity formed by the mold halves is large enough to accommodate thestacked assembly in a manner that the components making up the stackedassembly will be at least partially encased and held together by resinintroduced into the cavity. The mold may be provided with structures toimpart desired features to the molded resin component 15. Suchstructures can, for example, produce information indicia, handles,slots, windows, or any other features commonly present in plastichousings. For example, mold 25 includes raised portion 35 against whichdisplay 12 is placed when the stacked assembly 20 is placed within mold25. Raised portion 35 forms a window in molded resin component 15 toallow viewing of display 12 in the final electronic device 10. Once themold halves close, connector 19 is compressed by the mold halves and thecomponents are held in proper alignment with display 12 pressed againstraised portion 35 of mold 25.

The molds may include other features conventionally found in moldingdevices such as, for example, alignment pins, ejector pins, channels foraccommodating cooling fluids, and baffles or other means for directingthe flow of resin.

Resin is introduced into the mold cavity to form a monolithic resincomponent 15 that partially encases the electronic components of thedevice. Preferably, the resin is introduced into the mold while in afluid (e.g., molten or uncured) state. The resin employed can be any ofthe resins commonly employed in molding applications. Preferably, theresins are moldable at temperatures below about 500° F. Exposure of thecomponents to such temperatures generally does not adversely affect thecomponents since most electronic components are designed to be exposedto temperatures employed in soldering which can range from 350° F. to600° F. for short periods of time. Suitable resins for molding includeany of the known thermoplastic resins such as, for example, polyolefins,polyamides, polyesters, fluoropolymers, polyacrylates, polyacetates,polycarbonates, polyurethanes, polystyrenes, polyacrylonitriles, liquidcrystal polymers or any other engineering thermoplastic. Also suitableare a wide range of thermosetting resins, including, but not limited toepoxy resins, such as, for example, epoxy-novolacs, thermosettingpolyester resins, and thermosetting polyimides. Additionally, thestrength of the resulting molded resin component may be increased byusing a resin having a particulate (e.g., fibrous or spherical) fillerincorporated therein.

The resin may, but not necessarily, fill all voids between thecomponents. Known molding processes such as gas assist or co-injectionfoam molding may be employed to achieve substantially complete fillingof any voids or inter-component gaps. By completely encasing thecomponents, the resin locks the components into a desired position andthe resulting electronic device is much more mechanically robust andless likely to be damaged during handling or if dropped. If all voidsbetween components are not filled by the resin, structural supports (notshown) may be provided on the components to assist the assembly inwithstanding the compressive forces from the mold or forces from theflow of resin. Alternatively, it is contemplated that a inter-componentgap filler 13, such as, for example, a sheet of material, may beprovided between the components during preparation of the stackedassembly. It is also contemplated that the inter-component gap may beeliminated by planarizing the components, for example, by applying apre-coat to one or both sides of each component. Use of structuralsupports or an inter-component gap filler are a matter of design choice,which may be dictated by cost considerations, e.g., where the cost ofthe resin material used in molding justifies only partial encasement.

The resin is allowed to harden or cure within the mold. This ensuresthat molded, monolithic resin component 15 maintains any compressiveforce necessary for reliable contact to be provided by the connector(s).Being molded directly around the components, resin component 15 alsoprovides a good seal, making the resulting device environmentallyrobust, e.g., less sensitive to dust, moisture or other environmentalcontaminants, compared to devices including separately formed housings.Furthermore, the rigid alignment of the components helps eliminate anyshearing between them.

It is contemplated that any molding technique may be employed to producemolded, monolithic resin component 15. Such techniques include, by wayof exemplification only, injection molding and transfer molding. Thoseskilled in the art will envision how the present methods can be adaptedfor these and other molding techniques.

Additionally, while the foregoing discussion related to a two componentassembly for making an electronic device, it is contemplated that anynumber of components could be employed in making electronic devices inaccordance with this disclosure. For example, in the embodiment shown inFIGS. 5 and 6, four components 116A, 116B, 116C and 116D are used in thedevice. Component 116A includes a pair of hook members 117 thereon. Hookmembers 117 allow component 116A to be suspended on an alignment means,such as rods 118. Prior to suspension on rods 118 a compressionconnector 119 is secured to component 116A, e.g., by adhesive. Each ofcomponents 116B, C and D are likewise provided with hook portions forreceiving rods 118.

As best shown in FIG. 5, when components 116A-D are positioned on rods118, they are positioned generally between two mold halves 125, 145, atleast one of which is moveable. As the mold halves close, they causecomponents 116A-D to slide along rods 118 until the components are movedinto a properly aligned, stacked orientation within mold cavity 127. Asthe mold halves continue to close, the stacked components are compressedan amount to ensure that reliable connection is provided by compressionconnectors 119. Once the mold is closed, rods 118 can be withdrawn sincethe mold halves will hold the components together in the properorientation. Resin is then introduced into the mold cavity 127. Theresin is allowed to harden or cure within the mold. The mold halves arethen opened as shown in FIG. 6 and the finished electronic device 110 isremoved.

It is further contemplated that the process for making electronicdevices in accordance with this disclosure can be substantiallyautomated. Specifically, the sequence of steps, e.g., componentaligning, placement into the mold, mold closing, molding, productejection and transporting the finished product from the mold, can becontrolled by a programmable controller. The process shown in FIGS. 5and 6 is particularly suited to automation. Specifically, components116A-D can be automatically positioned onto rods 118, e.g., dropped froma conveyor belt or placed by a robotic arm. The sequence of moldingsteps, e.g., mold closing, withdrawal of rods 118, introduction ofresin, opening of the mold, and transporting the finished device awayfrom the molding site can each be computer controlled.

It will be understood that various modifications may be made to theembodiments disclosed herein. For example, where the electronic deviceis a modular unit to be incorporated into a larger electronic device orassembly, the portion of the components not encased by the molded resinmight only be a series of edge connectors. As another example, otherlayers or coatings, such as an impact absorbing elastomeric coating, maybe applied to all or a portion of the device after or concurrently withformation of the molded resin component. As yet another example, foamedresins may be employed in forming the molded resin component. It is alsocontemplated that conductive adhesive can be used as the connectorbetween the components. Therefore, the above description should not beconstrued as limiting, but merely as exemplifications of preferredembodiments. Those skilled in the art will envision other modificationswithin the scope and spirit of the claims appended hereto.

What is claimed is:
 1. An electronic device comprising: a firstelectronic component board; a second electronic component boardpositioned adjacent to the first electronic component board; a connectorfor providing electrical contact between said first and secondelectronic component boards; and a monolithic molded resin component atleast partially encasing together both said first and second electroniccomponent boards, the monolithic molded resin component maintaining theconnector in a compressed state between the first and second electroniccomponent boards to ensure a continuous electrical connection betweenthe first and second electronic component boards, wherein the secondelectronic component board is spaced apart from the first electroniccomponent board so as to define a gap therebetween, and wherein themonolithic molded resin component at least partially occupies said gap.2. A device as in claim 1 wherein the connector is a compressionconnector.
 3. A device as in claim 2 wherein the connector is anelastomeric connector.
 4. A device as in claim 1 wherein the moldedresin component is made from a polymer selected from the groupconsisting of polyolefins, polyamides, polyesters, fluoropolymers,polyacrylates, polyacetates, polycarbonates, polyurethanes,polystyrenes, polyacrylonitriles and liquid crystal polymers.
 5. Adevice as in claim 1 wherein the connector is a rigid connector.
 6. Anelectronic device as in claim 1 wherein said first and second electroniccomponent boards are selected from the group consisting of displays,printed circuit boards and input devices.
 7. A device as in claim 1wherein the molded resin component is made from a resin selected fromthe group consisting of thermoplastic and thermosetting resins.
 8. Adevice as in claim 1 further comprising an intercomponent gap filler foroccupying a portion of the gap not occupied by the monolithic resincomponent.
 9. A device as in claim 8 wherein the intercomponent gapfiller is in the form of a sheet.
 10. A device as in claim 8 wherein theintercomponent gap filler is a planarizing pre-coat applied to at leastone side of at least one of the components.
 11. In an electronic deviceincluding a first electronic component board and second electroniccomponent board in electrical contact through a compression connector,the improvement comprising a monolithic resin component molded aroundand at least partially encasing together both the first and secondelectronic component boards, the resin component maintaining thecompression connector in a compressed state between the first and secondelectronic component boards, wherein the second electronic componentboard is adjacent to and spaced apart from the first electroniccomponent board so as to define a gap therebetween, and wherein themonolithic resin component at least partially occupies said gap.
 12. Adevice as in claim 11 wherein the compression connector is anelastomeric connector.
 13. A device as in claim 11 wherein the resincomponent is made from a resin selected from the group consisting ofthermoplastic and thermosetting resins.
 14. A device as in claim 11wherein the resin component is made from a polymer selected from thegroup consisting of polyolefins, polyamides, polyesters, fluoropolymers,polyacrylates, polyacetates, polycarbonates, polyurethanes,polystyrenes, polyacrylonitriles and liquid crystal polymers.
 15. Adevice as in claim 11 further comprising an intercomponent gap fillerfor occupying a portion of the gap not occupied by the monolithic resincomponent.
 16. A device as in claim 15 wherein the intercomponent gapfiller is in the form of a sheet.
 17. A device as in claim 15 whereinthe intercomponent gap filler is a planarizing pre-coat applied to atleast one side of at least one of the electronic component boards.
 18. Adevice as in claim 11 wherein the first and second electronic componentboards are selected from the group consisting of displays, printedcircuit boards and input devices.
 19. A device as in claim 11 comprisingmore than two electronic component boards at least partially encasedtogether in a molded resin component.
 20. An electronic devicecomprising: a first electronic component board; a second electroniccomponent board; connector means for providing electrical contactbetween said first and second electronic component boards, the connectormeans being fixedly bonded to no more than one of the first and secondelectronic component boards; and a monolithic resin component moldeddirectly around and at least partially encasing together both said firstand second electronic component boards, wherein the second electroniccomponent board is adjacent to and spaced apart from the firstelectronic component board so as to define a gap therebetween, andwherein the monolithic resin component substantially completely occupiessaid gap.
 21. The electronic device of claim 20 wherein the connectormeans is fixedly bonded by means of adhesive.
 22. An electronic devicecomprising: a first electronic component board; a second electroniccomponent board; connector means for providing electrical contactbetween said first and second electronic component boards; the first andsecond electronic component boards being monolithically encased togetherin a molded resin component, wherein the second electronic componentboard is spaced apart from the first electronic component board so as todefine a gap therebetween, and wherein the monolithic resin componentsubstantially completely occupies said gap.
 23. An electronic devicecomprising: at least three electronic component boards oriented in astacked array and being spaced apart from each other so as to define agap between respectively adjacent electronic component boards, eachelectronic component board being electrically connected to the adjacentelectronic component boards by a respective one of at least twocompressible electrical connectors; a monolithic resin component moldeddirectly around and at least partially encasing together the stackedarray of electronic component boards, the resin component maintainingthe electrical connectors in a compressed state to ensure a continuouselectrical connection between the respective adjacent electroniccomponent boards.
 24. The device of claim 23 wherein the monolithicresin component at least partially occupies the gaps between theadjacent electronic component boards.